Communication systems are known in which a communication network including a plurality of nodes is managed centrally by a management server. On receiving a request to set a path related to traffic, the management server determines a communication path for the traffic in question in the communication network. In the following, a management server that determines the communication path for traffic is referred to as a “control server.”
In a communication network that includes a plurality of nodes, a power supply for the nodes is always in an ON state, in preparation for the generation of traffic. This type of power supply management method is effective in an environment with a high frequency of traffic occurrence. However, in an environment with a low frequency of traffic occurrence, the node usage rate is low, the nodes are not used effectively, and electrical power is consumed unnecessarily in the communication network.
To reduce the power consumption of a communication network in an environment with a low frequency of traffic generation, it is preferable to shut off the power supply of nodes with a low rate of usage, or to go into a power saving mode. Furthermore, in this case it is necessary not to reduce throughput provided for traffic. In an environment with a low frequency of traffic generation, as an example, the following technology is known for shutting off the power supply of nodes with a low rate of usage or for going into a power saving mode, while providing adequate throughput for traffic.
PTL 1 describes a method in which traffic volume is measured at an edge portion of a communication network, and if the traffic volume is low, nodes are transitioned to a power saving mode and routing is performed to circumvent the nodes that have transitioned to the power saving mode.
NPL 1 describes an energy-aware routing method where, with a state in which there is input from all power supplies as an initial state, path calculation for equal-cost multi-path is performed, estimated average throughput of traffic in the initial state and estimated node usage rate are calculated, the power supply of nodes having the lowest estimated node usage rate is shut off, and power supply shutoff and comparison of estimated average throughput are performed until the estimated average throughput of the traffic in a network, in which nodes that have power supply shut off are removed, is not greater than a fixed number of times the estimated average throughput in the initial state. According to this method, it is possible to shut off the power supply of nodes with low rates of usage while maintaining throughput.
PTL 1:
Japanese Patent Kokai Publication No. JP-P2010-148023A
NPL 1:
Yunfei Shang, Dan Li, Mingwei Xu, “Energy-aware Routing in Data Center Network,” Proceedings of ACM SIGCOMM 2010 Workshop on Green Networking.
NPL 2:
Nick McKeown, et al., “OpenFlow: Enabling Innovation in Campus Networks,” [online], [search conducted Mar. 30, 2011] Internet URL:
http://www.openflowswitch.org//documents/openflow-wp-latest.pdf
NPL 3:
Y. Honma, M. Aida, H. Shimonishi and A. Iwata, “A New Multi-path Routing Methodology Based on Logit Type Assignment,” Proceedings of the 2nd International Workshop on the Network of the Future (FutureNet II), 2009.